Conservative government watchdog group Judicial Watch is leading two liberal groups in an explosion of Freedom of Information Act (FOIA) lawsuits, seeking to force federal officials to publicize thousands of previously hidden documents, according to a new study by The FOIA Project.

“Even a casual perusal of the plaintiffs in FOIA suits filed week after week reveals that there are a small number of advocacy organizations that appear again and again,” The FOIA Project said in a statement Thursday.

“Indeed, the widely recognized champion among FOIA filers is Judicial Watch, Inc. … this single organization has been responsible for an astounding one out of every five FOIA lawsuits filed by all nonprofit groups since 2001,” the statement added. The group’s data covers a 16-year period, from 2001 to April 2017.

Judicial Watch filed 324 FOIA law suits. Second and third, respectively, on the list of nonprofit advocacy groups filing FOIA suits are the American Civil Liberties Union with 117 suits and Citizens for Responsibility and Ethics in Washington with 77 suits.